9 Weird Things Your Penis Does

by Joshua Shoemake

Dec 20, 2014

You shake and bounce, but a stray drop or two of pee still trickles into your underwear as you leave the restroom. Is the O-ring in your penis defective or something?

“I talk to men all the time who worry about this, but it’s not a big deal,” says Joseph Sonstein, M.D., a urologist with the University of Texas Medical Branch. (Whew.) Your urethra—the hollow tube that carries urine from your bladder to the tip of your penis—forms a slight upside-down U shape, Dr. Sonstein explains. And there’s inevitably a little pee left over in your U when you finish urinating, which gravity causes to leak out after you’ve zipped up, he adds.

“It can be a bigger problem for men who have a weak stream, because the lack of force leaves more pee behind to dribble out,” Dr. Sonstein adds. A weak stream could be a sign of an enlarged prostate or inflammation, which is common among older guys. But for most young men, a little leakage is nothing to stress about.

Why does some semen always show up late to the party?

Like that drop or two of leftover urine, some ejaculate leaks out a few minutes after you’ve had an orgasm. Dr. Sonstein says the explanation is the same as before: “Semen is just a little more viscous, so it takes more time for gravity to work it out of your urethra,” he says.

Why does your penis shrink when wet?

Despite what George Costanza says, it’s not the wetness that does it. It’s the chill of exposing your genitals to cool air or water that causes the “shrinkage,” Dr. Sonstein says. Your scrotum hangs outside of your body because your sperm need very specific temperatures to thrive. Muscles in your scrotum and along the “spermatic cord” that leads down from your penis to each testicle contract when you’re cold, pulling your scrotum up toward your body. And this contraction tightens your penis muscles and tissue as well, shrinking it, Dr. Sonstein says. (The opposite happens when you’re hot, causing your testicles and penis to hang farther from your body, he adds.)

Why do you pitch a tent every morning?

Your testosterone levels peak in the A.M., which explains your perky member, Dr. Sonstein says. There’s also some evidence you become erect—even when you’re not aroused—in order to maintain proper sexual function. “It’s sort of the old ‘if you don’t use it, you lose it’ thing,” Dr. Sonstein adds. So that explains your otherwise curious midday, driving-in-your-car boners.

Why do some men experience “wet dreams”?

Again, this is probably the result of elevated testosterone levels, which rise while you sleep, says Dr. Sonstein. “That’s why adolescent men, whose testosterone levels tend to be really high, experience more wet dreams than older men.” Dr. Sonstein says there’s some anecdotal evidence—but no proof—that wet dreams occur more often when a lot of time has passed between your orgasms, and so this could be your body’s way of making room for fresher sperm supplies.

Why does your urine sometimes shoot out at a strange angle?

Your urine stream’s “crazy Ivan” schtick tends to occur after sex, after masturbation, or in the morning if you ejaculated just before bed—or while you slept—Dr. Sonstein says. Why? It’s nearly always because a little semen is still hanging out in your urethra from your last orgasm, which creates an obstruction. If the odd angle doesn’t go away soon, it could be a sign of scar tissue or an STD, Dr. Sonstein adds.

Why do some men’s penises become so much larger when erect, while others’ grow very little?

Maybe you’ve heard some guys are “growers, not showers.” At least anecdotally, that seems to be true. “Men who are smaller when flaccid tend to get much longer when erect,” Dr. Sonstein says. “Whereas men who are long when flaccid tend to get harder, but not that much bigger. It’s all just genetics.”

Why is urine yellow regardless of what you eat or drink?

Urine contains a chemical called urobilin, which is involved in the breakdown of fluid that takes place in your kidneys, says Dr. Sonstein. Urobilin is yellow, and the more of it you see in your pee, the less that biochemical is being diluted by water or other fluids you drink. If you’re properly hydrated, healthy urine should actually be pretty close to clear, Dr. Sonstein explains.

Once or twice, you’ve had a problem getting an erection during sex. What gives?

This is called “situational erectile dysfunction,” and a ton of guys experience it, Dr. Sonstein says. “Usually it’s stress- or relationship problem-related.” If you’re feeling a lot of pressure or anxiety, it can tense you up to the point that you have problems getting hard. Dr. Sonstein says if it gets really bad, he’ll occasionally prescribe a low dose of an ED drug like Viagra to help a patient get his confidence back.